Kagome-fiber-based pulse compression of mid-infrared picosecond pulses from a Ho:YLF amplifier

Abstract

Over the last decade, the development of ultrafast laser pulses in the mid-infrared (MIR) region has led to important breakthroughs in attosecond science and strong-field physics. However, as most such broadband MIR laser sources are near-IR pumped, the generation of high-intensity, long-wavelength MIR pulses is still a challenge, especially starting from picosecond pulses. Here we report, both experimentally and numerically, nonlinear pulse compression of sub-millijoule picosecond pulses down to sub-300 fs at 2050 nm wavelength in gas-filled Kagome-type hollow-core photonic crystal fibers for driving MIR optical parametric amplifiers. The pump laser is comprised of a compact fiber laser-seeded 2 μm chirped pulse amplification system based on a Ho:YLF crystal at 1 kHz repetition rate. Spectral broadening is studied for different experimental conditions with variations of gas pressure and incident pulse energies. The spectrally broadened 1.8 ps pulses with a Fourier-limited duration of 250 fs are compressed using an external prism-based compressor down to 285 fs and output energy of 125 μJ.

Hollow-Core Fiber Technology: The Rising of “Gas Photonics”

“…To date, it represents the strongest compression ratio in self-compression regime with a value of 17 that has been achieved using HCPCF technology. [114] 790 nm Self-compression 6.6 µJ 24 fs 6.8 fs~3.5 Krypton Hädrich et al [106] 1030 nm Postcompression 9 µJ 250 fs 30 fs~8.3 Krypton Guichard et al [115] 1030 nm Postcompression 70 µJ 330 fs 34 fs~9.7 Ambiant air Debord et al [31] 1030 nm Self-compression 450 µJ 600 fs 49 fs~12 Ambiant air Emaury et al [116] 1030 nm Postcompression 1.95 µJ 860 fs 48 fs~17.9 Xenon Balciunas et al [16] 1080 nm Self-compression 35 µJ 80 fs 4.5 fs~17 Xenon Wang et al [61] 1500 nm Self-compression 105 µJ 850 fs 300 fs~2.8 Ambiant air Gebhardt et al [117] 1820 nm Self-compression 41 µJ/34.4 µJ 110 fs 14 fs~7.8 Argon Murari et al [118] 2050 nm Postcompression 227 µJ 1.8 ps 285 fs~6.3 Argon…”

Novel method for the angular chirp compensation of passively CEP-stable few-cycle pulses

“…The fiber was in air, only 22-cm long in order to avoid unwanted nonlinear effects, with 7-core cells and 63-µm core diameter. The numerical aperture (NA) was ∼0.018 [29], therefore its acceptance angle was ∼2°. The output energy after the fiber was 3.8 µJ, so the coupling efficiency was 36%.…”

“…It produces 5.4-mJ, 650-fs pulses at 1030 nm with 1 kHz repetition rate. We pumped and seeded a DOPA centered at 2 µm, and focused the idler into a HCPCF, in particular an inhibited coupling Kagome fiber [29] used in the linear regime. At the output of the fiber, the CEP-stable broadband idler has a well-defined propagation direction and no detectable angular chirp, and can be directly utilized as a seed for successive DOPA stages.…”

Novel method for CEP-stable seeding of few-cycle OPCPAs

“…In this work, we introduce a novel scheme which allows saving pump energy for the generation of a few-cycle CEP-stable seed for a single channel OPCPA chain. The method consists in using a broadband non-collinear OPCPA with a strongly angularly-chirped idler and focusing it into a Kagome fiber [6]. The Kagome fiber is used in a linear regime and it homogenizes the wave-vector directions of all idler wavelengths, similarly to the technique used for homogenizing diode lasers [7].…”